Dynamic balance tester



Nov. 28, 1950 T. CARRIGAN 2,532,056

DYNAMIC BALANCE TESTER Filed Jan. 8, 1946 5 Sheets-Sheet 1 F'IIEI' -1 I I 4 I y Li /90 Lwe TRACY CAIZQ/GAN Nov. 28, 1950 T. CARRIGAN 2,532,056

DYNAMIC BALANCE TESTER Nov. 28, 1950 T. CARRIGAN DYNAMIC BALANCE TESTER 5 Sheets-Sheet 4 Filed Jan. 8, 1946 3mm 7 2Acx CARZIGAN. M

Patented Nov. 28, 1950 DYNAMIC BALANCE TESTER Tracy Carrigan, Lansing, Mich., assignor to Food Machinery and Chemical Corporation, a corporation of Delaware Application January 8, 1946, Serial No. 639,803

(Cl. B -66) 14 Claims. 1.

This invention relates to machines for testing the balance of rotative bodies, such as automobile wheels.

The invention herein is particularly concerned with improvements in dynamic balance testers for indicating the amount and location of dynamic unbalance in rotative bodies.

In- 'prior known dynamic balance testers it has been the practice to employ a detector mechanism adapted to engage the rotating body to be tested to transfer vibrations therefrom to an indicator mechanism. This is commonly accomplished by the use of an actuating mechanism which mechanically engages the body; or by an indicator actuating pi'n which contacts a wobble late associated with the body. In body engaging detectors indication takes place only while the body is rotating and correction can only be made after the body ceases rotating, consequently correction of the dynamic unbalance thereof must be made from memory. In wobble plate contacting indicators an accurate indication of thelocation and amount of dynamic unbalance is given only when the diametrical axis of the body on which the dynamic unbalance is located is in a predetermined position relative to the indicator.

In balance testers employing either of the above types of detector mechanisms a stationary member must mechanically engage a movable member and, therefore, both members are sub ject to considerable wear requiring frequent inspection and adjustment.

One object of the present invention is to provide an improved dynamic balance tester wherel in the mechanical indicator mechanism has been eliminated and which is of simple and economical construction and highly efficient in use.

Another object is to provide a balance testing apparatus with an optical indicator for portraying the amount and location of dynamic unbalance of the body tested after the body ceases rotating.

Another object is to simulate the wobble of a dynamically unbalanced body after the body ceases wobbling and to reflect an image of a light beam onto a screen in accordance with the simulated wobble thereby registering the amount and location of dynamic unbalance of the body.

A further object of the invention is to provide dynamic unbalance of the body so that when the body and reflector are subsequently rotated about a predetermined axis the reflector will cast an image of a light beam projected thereonto, at an angle in proportion to the amount, and in a direction dependent upon the location of the dynamic unbalance of the body.

Other objects and advantages of the present invention will appear more fully in the following description in connection with the drawings in which: i

Fig. 1 is a top view of a wheel balancer embodying the present invention and having a wheel mounted thereon with its axis horizontal.

Fig. 2 is an enlarged horizontal section of Fig. 1, the view being taken along lines 2'2 of Figs. 3 and 4.

Fig. 3 is a fragmentary vertical section taken along line 3-3 in Fig. 2.

Fig. 4 is a fragmentary vertical section taken along line l4 in Fig. 2.

Fig. 5 is a cross-section taken along line 5- -5 in Fig. 4.

Fig. 6 is a fragmentary elevational view taken substantially along line 6-45 in Fig. 5.

Fig. 7 is an enlarged section of a portion of Fig. 5 taken along line 'll' thereof.

Fig. 8 is an enlarged detail view taken along line 8-8 in Fig. 1.

The present invention is adapted for general application with various designs of dynamic balance testing machines. For purposes of this disclosure the invention has been illustrated in conjunction with a wheel balancer of the type disclosed in U. S. Letters Patent No. 2,349,552 issued May 23, 1944, to H. G. Holmes. Since the construction and operation of the Holmes machine is clearly disclosed in the patent referred to, only so much of the Holmes wheel balancer will be described herein as necessary for a proper understanding of the present invention.

The wheel balancer embodying the present invention (Figs. 1 to 5) comprises a frame 6 including a base casting i having a vertically disposed cylindrical flange 3 and a tripodal foot 9 formed integral therewith. The foot 9 (Figs. '2, 4 and 5) comprises two feet Ill and II which extend laterally from the flange 8 and are braced by diagonal webs l2 and 13, respectively. and a foot I l which extends rearwardly from the flange 8 and is braced by a diagonal web l5.- Each foot has a hole It therein to receive a bolt, not shown, whereby the base casting can be bolted to the floor upon which it is to rest.

The cylindrical flange 8 receives and supports the lower end 24 of a column 25. A depending flange 25 of a head casting 27 (Fig. 4) fits into the upper end of column 25 and the head casting is secured. to the base casting by a pair of tie rods 28 and 25. Both tie rods are identical and are spaced from each other within the column 25 transversely of the longitudinal axis of the base casting I. As shown for example by the tie rod 29 in Fig. 4, the tie rods are threaded into the head casting from below and have their threaded lower ends extending down through apertures in the base casting. The lower end of each tie rod receives a nut 30 whereby the column, the base casting and head casting are suitably fastened together.

The lateral feet in and II are provided with a rearwardly extending flange 4B and 4!, respectively (Figs. 2 and These flanges 55 and ll are recessed to receive an inwardly disposed horizontal flange of an angle 63 and 44, respectively, which is secured thereto by a bolt 42. These angles 43 and 55 extend rearwardly from the feet is and M, respectively, and have their vertical flanges extending downwardly at the sides of the frame. The angles 43 and 44 (Figs. 2 and 3) are welded at their rearward ends to a back angle 45. The midportions of angles 43 and 44 are braced by a transverse angle 45 having its respective ends welded to the side angles in a manner to position the vertical flange l? of angle 45 in abutment with the end of the foot M to which it is secured by cap screws 55 (Fig. 4).

At the rear corners of the frame there are upstanding angles 49 and 55 having their lower ends welded to the respective side angles 43 and 54 and the adjacent end of the back angle 55. At each side of the frame is an upstanding leg 5| and 52, respectively, in the form of an elongated plate having its lower end welded to the respective side angle 43 and 44 adjacent the transverse angle 46. At the forward end of each of the side angles 43 and 44 there is a vertical strut 53 and 54, respectively, each having its lower end welded to the respective side angle and its upper end disposed in the same plane as the upper ends of the legs 5i and 52.

The upper portion of the frame is formed by a continuous strap 55 havingat the ends thereof inwardly extending flanges 55, and 5'5, respectively. As seen in Fig. 2 the head casting 2'! has a pair of laterally extending flanges 58 and 59 to which the strap flanges 55 and 51, respectively, are bolted as shown at 69. The strap 55 is bent at approximately 45 adjacent its flanges 56 and 51 and is again bent 45 just in advance of its convergence with the upper end of the vertical struts 53 and 54 so that it rests upon the latter. The bottom edge of the strap 55 is welded to the upper end of the respective struts 53 and 54 and is also welded to the upper ends of the legs 5| and 52 referred to above. The mid-portion of the strap 55 continues around the rearward side of the frame and rests on the upper ends of the corner angles 49 and 55 to which it is welded. The frame 5 is completed by a transverse U-channel 55 extending flanges down between the upper ends of the legs 51! and 52. This channel 65 has its ends welded to the strap 55 so that the upper face of the channel is in the same plane as the upper edge of the strap.

I An adjustable body support, indicated generally at (Figs. 1 and 4), is mounted in the frame above the column 25. This body support comprises an arbor "H having suitably secured thereto between its ends, a trunnion block i2 having axially aligned trunnlons l5 and '35 ex tending laterally therefrom. The head casting 21 has formed integrally therewith the lower half of a trunnion carriage 15 which supports the trunnions '33 and i i. A pair of caps and i? forming the upper half of the trunnion carriage are bolted to the lower half thereof as shown at 18. The trunnion carriage is provided with friction type bearings (not shown) which clamp sufficiently tight around the trunnions l3 and. 14 to support the arbor so that it can be readily shifted by hand from vertical to horizontal position and vice versa, but is not free to do so unless some external force is exerted upon it. In order to permit the foregoing movem nt of the arbor the head casting 2'5 and the rearward side of the upper end of the column 25 are both slotted as shown at 55 (Fig. 5).

The movement of the arbor between its two extreme positions is cushioned in the same manher as shown in the aforementioned patent by a pair of compression springs each encompassing the respective tie rods 28 and 25 mentioned above. For example as seen in Fig. 4 one compression spring 82 is arranged on the tie rod 29 to bear against the under side of the head casting 2! and a cross head is slidably arranged on the tie rods to bear against the lower ends of the springs. The cross head 83 is pivotally connected to double links 55, the opposite ends of which are pivotally connected to a lug 85 secured to the lower portion 15 of the arbor.

The arbor H is held in the two extreme positions in the same manner as shown in the Holmes patent. When in its vertical position the arbor is held by a latch pivotally connected at 9| to the lower extremity of the arbor and having a slot 92 to receive a pin 53 extending between cars 94 formed on the column 25. Th latch also has a recess 95 communicating with the slot 92 and a leaf spring 56 engaging the arbor H is secured to the upper edge of the latch so as to maintain the latch in engagement with the pin 93 and to seat the same in the recess 95. This latch is released in the same manner and for the same purpose as in the aforementioned patent by a push rod I05 slidably arranged in brackets llll within the column 25. The lower end of rod Hill is pivotally connected at I99 to a lever I05 extending forwardly of the machine and through an aperture I68 in the cylindrical flange 8. The aperture H38 in the flange 8 provides a fulcrum for the lever I86 whereby the latter can be operated by pressing down upon a foot pedal secured to the free end of the lever.

The frame 6 is enclosed within a metal housing I H) which conforms to the general outline of the frame and is provided with the necessary openings to permit portions of the mechanism to extend through the housing. As seen in Fig. 4 the upper surface I H of the housing is in substantially the same plane as the upper edge of the trunnion carriage E5 hereinbefore referred to. As further seen in Figs. 1 and 5 there is a hump H5 formed on the upper surface of the housing above the column 25. This hump has a slot H6 formed therein corresponding to and diametrically opposite to the slot 80. The slot H6 is so disposed relative to the trunnions 73 and 14 as to permit movement of the arbor from horizontal to vertical position and vice versa as hereisbeiqre e p aine As seen in Fig. 3 the rearward portion of the housing is raised substantially above the upper surface III thereof to provide a table-like control panel I20. This control panel I is to the rear of the transverse channel 65 and extends laterally of the general outline of the frame as best seen in Figs. 1 and 2.

The outer end of the arbor H has a bushing '-I 2I arranged thereon for reciprocable movement relative thereto. Secured to the lower portion of the bushing I2I is a reciprocable hub I22 while the upper portion of the bushing has secured thereto the inner race I23 of a ball bearing unit I24. A compression spring I25 is arranged on the arbor and rests upon the bushing I2I. An inverted frusto-conical collar I26 bears against the spring I25 and is held thereagainst by a snap ring I21 seated in an annular groove I28 in the arbor. In this manner the bushing and reciprocable hub are continually urged downwardly into yielding engagement with curbings I29 and I30 formed on the two trunnion caps 16 and 11, respectively, adjacent the margins of the slot I 16.

The arbor II extends through the slot IIE in the hump IIii of the housing H0. The outer end of the arbor is provided with a shoulder I3I against which the inner race of a self-aligning ball bearing I32 is held by a washer I33 and a cap screw I34. A spindle I35 having its inner end formed as a hollow cylindrical quill I38 fits over the arbor. The spindle I35 is supported on the outer race I31 of bearing I32 thus permitting universal tilting movement of the spindle relative to the vertical axis of the arbor.

The open end of the quill has a counterbored portion I38 which is adapted to receive the outer race I39 of the ball bearing unit I24 heretofore referred to. The inner end of the spindle has an external shoulder I40 adjacent the open end thereof as seen in Fig. 4 and a collar I lI firmly fits over the quill and rests on the shoulder I60. This collar has its peripheral edges I43 and I43, adjacent its parallel top and bottom surfaces, respectively, ground to present a frustum of a sphere having a central peripheral band of cylindrical shape.

A wobble plate I45 having a hub portion I 39 freely encompasses the collar I II and is frictionally held in place thereon by a series of leaf springs I41. The leaf springs are secured inside the hub I46 in equally spaced grooves [d8 formed in a flange I49 extending inwardly from the upper edge of the hub. The inner face I5! of the flange I49 is ground to fit over the spherical surface of the upper peripheral edge I43 of the collar I4I so that the upper edge of the hub is slightly below the upper edge of the collar. The free ends of the leaf springs I41 are bent inwardly to frictionally engage the spherical surface of the lower peripheral edge I 34 of the collar. The leaf springs I411 frictionally engage the collar to maintain the wobble plate in adjusted position relative to the collar but permit tilting of the same about the collar when an outside force is applied to the wobble plate.

A leveling plate or equalizer in the form of a washer I is arranged on the spindle over the collar MI and extends over the upper edge of the hub I45 to limit the tilting of the wobble plate. A cone I69 is arranged on the spindle to hold the washer I55 in place and has a lower internal flange IISI and an upper internal flange I62 each of which engage the spindle exteriorly of the quill.

A wheel I65 with a tire I63 thereon is mounted on the spindle with the outer race 1610f the inner wheel bearing seated on the cone I60. A second cone I 68 having a bore I69 fits over the spindle shank and seats in the outer wheel bearing I10. A washer I1'I is arranged on the threaded end of the spindle shank which receives a nut I 12 for securing the wheel in axial alignment with the spindle.

A vertically disposed bushing I15, Figs. 2, 3 and 4. is arranged on the transverse channel 65 to one side of the longitudinal axis of the frame- This bushing I15 has its upper portion welded at I16 to the rear-ward flange I11 of the channel 65 with the upper face of the bushing flush with the top surface of the channel web. The bushing is further secured to the channel by a brace plate I18 extending forwardly therefrom and having its upper edge welded to the flanges'and web of the channel.

A swinging bracket I is mounted on the bushing I15. This bracket has bosses I81 and I82 in axial alignment with the bushing and bore to receive the ends of a spindle I83 extending through and secured to the bushing by set screws I84. The outer end of the bracket I80 has a vertical boss I85 formed thereon to receive the lower end of a tubular pole I86. The boss I 89 is split at I81 and is tightly clamped upon the pole I86 by bolts I88 to firmly secure the pole to the bracket I80.

Arranged on the pole I86 is a split boss I89 of a bracket I90 which split boss I 89 is tightly clamped to the pole by bolts Hi. The bracket I90 extends through an opening I92 formed in a vertical wall I93 at the forward side of the control panel I20 (Fig. 4). The outer end of the bracket I30 has bolted thereto at I94 an electric motor I95 to support the same for swinging movement above the frame and in an arcuate slot I96 formed in the upper surface III of the housing as is best seen in Figs. 1 and 4. The motor has a drive shaft I91 extending upwardly therefrom and keyed to this shaft is a drive pulley I98 having its outer periphery disposed to tractionally engage the tread of the tire I66 when the bracket I80 is swung toward the same.

The upper end of the pole I86 is reduced to provide a shoulder 200 and to receive and support a sleeve shaft 20! for rotation thereon. Secured to the sleeve shaft by set screws 202 is the hub portion 203 of a laterally extending brake shoe 204 which also extends through the opening I92 in the wall I93. A brake lining 205is secured to a concaved face 206 of the brake shoe and is adapted to frictionally engage the drive pulley I98 when the sleeve shaft is swung counterclockwise as seen in Fig. 1.

The free end of the pole and the sleeve shaft 20I extend up through an arcuate slot 201 in the control panel I20 a sufficient distance to pro-.

vide a vertical handgrip whereby the bracket I80 can be manually swung toward and away from the wheel I65. Secured to the upper end of the sleeve shaft 20I is a handle 208 whereby the sleeve shaft and brake can be swung relative to the pole I86.

The handle 208, as seen in Fig. 8, is hollow and has a toggle switch 209 secured therein by screws 2I0. Electric current is supplied from a power supply line as seen in Fig. 3 by way of a main plug 2II having lead-in wires 2| 2 and 2I3. The lead-in wire 2I3 is connected to a main switch 2 I4 mounted on the back wall of the housing I I0. A conductor 2I5 leading from the main switch 2I4 is connected to one binding post 2I6 ofa transformer 2II, mounted on the leg 52 of the frame 6. The conductor 2I5 extends from the binding post 2| 6 up through the tubular pole 186 for connection to one side of the toggle switch 209 in the handle 208. From the other side of the toggle switch 209 a wire 2I8 extends down into the tubular pole I86 and out of the same through an aperture 2I9 just below the shoulder 299 upon which the sleeve shaft 20I is supported. The wire 2 I8 is connected to the motor I95 which in turn has connected thereto a wire 229 leading back through the aperture 2 I 9 and down through the pole I86 for connection to the other binding post 22! of the transformer 2". The binding post 22! is directly connected to the lead-in wire 2I2 extending into the housing from the main plug 2| I.

' As shown in Figs. 2 and 5, the trunnion caps '16 and H are provided with horizontally aligned bosses 239 and 23I to the rear of the arbor and supported in these bosses is a rocker shaft 232. The ends of this rocker shaft extend beyond the bosses 230 and 23: and have secured thereto the hub portion 233 of a rocker arm 234 and 235, respectively. The forward ends of the rocker arms 234 and 235 extend up through a slot 236 and 231, respectively, in the top surface III of the housing I ID on either side of the hump I I5. The free upper end of each rocker arm has an outwardly extending boss formation 238 and secured thereto by a cap screw 239 (Fig. 6) is a disc or relatively thick bronze washer 249. The rocker arm 235 has a rearwardly extending lever arm 245 with a clevis end 246 which embraces the forward end of an actuating lever 24?. The clevis end 245 is pivotally connected to the lever 24! by a headed pin 248 secured in place by a cotter pin 249.

The actuating lever 24'! is fulcrumed midway between its ends on a bolt 25 supported in an upstanding bracket 256 welded to the upper surface of the channel 65. As seen in Fig. 3 the opposite end 251 of the actuating lever 241 is twisted into a horizontal position and has anaperture 258 formed therein to receive the lower end of a plunger 260. The plunger 269 is threaded to receive bolts 26! and 262 having rounded heads engaging the upper and lower faces, respectively, of the horizontal end 251 of the lever 24'! to permit rocking movement and adjustment of the lever relative to the plunger. An' angle bracket 263 is welded to the forward flange of the channel 65 beneath the forward arm of the actuating lever 241 and a stop or bolt 264 is threaded up through the bracket 263 and held in adjusted position thereon by a lock-nut so that the downward movement of the forward arm of the lever is limited.

A compression spring 265 surrounds the plunger 259 and is seated on a retaining Washer 266 held in elevated position on the plunger by a cotter pin 29?. The upper end of spring 265 engages the lower face of the control panel i29 so that the plunger is urged downwardly. The plunger extends up through an opening in the panel I29 to receive a knob 269 which is secured to the plunger for limiting downward movement of the same under the influence of the spring 255. The knob 269 provides a finger grip whereby the plunger can be manually raised to rock the actuating lever 24? and rocker arms 234 and 235 to thereby raise the discs 249 toward the wobble plate I45. It will be noted that the periphery of the discs 24!! are ground arcuately toward the side faces thereof so as to form a ball-like surfacepnthe periphery of .the discs. It is further 8 7 to be noted that the discs 249 are eccentrically mounted relative to the cap screws 239 so that the discs can be adjusted to raise or lower their balllike surfaces relative to the wobble plate I45 Fig. 6.

Arranged within the housing H9 (Figs. 1, 2, 4 and 5) is an optical indicator generally designated 299 which includes a light source 29I, a projector 292, a reflector surface 293, a plurality of mirrors I, II, and III and a screen 294.

In the preferred construction as seen in Fig. 5 the light source is a 5 volt lamp 295 mounted in a socket 298, both of which are of a type generally known to the automotive industry. The socket 295 is supported on a bracket 29? secured at 298 to a bracket 299 bolted to the foot I I to the left of the column 25 (Fig. 5).

Electric current is supplied to the lamp 295 from the secondary winding of the transformer 2i? mentioned above. As explained above the primary winding of the transformer is connected to the power supply line and is controlled by the main switch 2M. As best seen in Figs. 3 and 4 one binding post 399 on the secondary side of the transformer is connected to a wire 395 which in turn, as seen in Fig. 5, is connected to a center contact (not shown) within and insulated relative to the socket 295. The socket is grounded through brackets 29'! and 295 to the frame 5 and the other binding post 392 of the secondary side of the transformer 2H is also grounded to the frame 5 thereby establishing a closed circuit to the 6 volt lamp 295.

Likewise secured to the bracket 29? is a U-shaped bracket 395 as shown in Fig. 5. The lower arm of the bracket 395 has an opening 396 including a shoulder 39? on which a concaved reflector 353 is held in place by a snap ring 399. The upper arm of the bracket 395 has a split sleeve Sit? which supports a projector tube 3H in a fixed position within the frame 6. The sleeve 359 is clamped onto the lower end of the projector tube by means of a cap screw 312 threaded through lateral ears SIB formed as a part of the split sleeve 3 I 9.

A U-shaped shield 3323, Figs. 5 and 7, is arranged on the bracket 395 to close the open end thereof and has its sides secured to the sleeve 3I9 by screws 32} so as to form a lamp housing around the light source 29 I A disc 322 is secured against the lower end of the projector tube by screws 323 and as best seen in Fig. 7 this disc has a pin hole or aperture 324 formed therein. The aperture 324 is in axial alignment with the projector tube so that a beam of light passes from the lamp 295 and silvered reflector 335 up through the projector tube 3i I.

The upper end of the projector tube 3| I has a cylindrical cap 325 secured thereto and mounted within this cap is an achromatic lens comprising a plano-concaved lens 326 seated on the end of the projector tube and a double-convex lens 321 overlying the plano-concaved lens. These lenses are held tightly against the upper end of the projector tube by an expansion ring 328 seated in an annular groove 329 formed in the inner wall of the cap 325.

The reflector surface 293 is carried by the wobble plate as best seen in Figs. 4 and 5, and is preferably a plate glass mirror 339. This mirror is of circular shape and has a central opening 33I formed therein as shown in Fig. 4 to surround but not touch the free ends of the leaf springs I41 of the wobble plate. The mirror 330 is secured against the lower face of the wobble plate by an adhesive or cement and the periphery of the mirror is guarded by a flan e 332 formed as a periphery of the wobble plate. The face of mirror is silvcred and protected by a transparent hard surface coating. It will be noted. in Figs. 4 and 5 that the projector tube 3! l is in a vertical plane transversely of the machine and is disposed at an angle across the machine to project a beam or light toward the rearward. porrtion of the mirror Therefore, when the. mirror 33d is normal position, i. e. perpendicular to the axis of the arbor 5!, the reflection of the light beam will be reflected in the same vertical plane as the projected light beam and downwardly at an or reflection corresponding to the angle of i rdence or the projected light beam relative to the mirror. This vertical plane which includes both the projected and the reflected beam light is the normal plane of incidence designated N along the line 55 of Fig. 4 and as seen in elevation in 5. The light beam as I'SflCJGd the m r is in the form of a light en ii whici ll produce a spot of light on which intercepts the same. This light pencil is ultimately directed toward the inner side of the screen which, in the present instance, is translucent panel capable of absorbing the 2' age or" the light spot caused by the light l to render thelight spot visible on the outer side cl the screen.

ill

As best seen in Figs. 1 and 3, the screen 294, is

arranged on an annular flange 33 formed in a depressed portion of the control panel I29 to one side of the longitudinal axis of the machine. The screen 29-3 is secured in place by flanged retaining ring 334 secured to the annular wall of the depressed portion of the panel by screws 3%. The entire light pencil is concealed within the housing llii so as not to diminish the intensity of the 7 light thereof. In order to properly direct the light pencil from the mirror 33% toward the screen in the present disclosure, the light pencil must again be reflected upwardly. For this purpose a main reflecting mirror, designated I, is disposed on a bracket 33% (Figs. 4i and 5) secured to foot ,I 0' adjacent to the column 25 opposite the projector and in the normal plane of: incidence Nso that a light pencil projected in said plane when the mirror 339 is level, strikes the mirror I at its center. This mirror I is so positioned that the aforesaid light pencil will be reflected in a plane ;R which is at right angles to the plane N (Fig. 2) and at an angle upwardly (Fig. e) in the direction of the screen 294.

Since the Variations in angle of reflection caused by tilting of the wobble plate M5 are slight, in order to perceive any appreciable difierence thereof the light beam must be projected a sulficient distance therefrornn In the present instance the distance between mirror I and the screen is increased by redirecting the pencil of light between the top and bottom of th housing several times.

In order to accomplish the foregoing, second and third mirrors are arranged in the plane R which includes the centers of both the screen and mirror I. The second mirror, designated mirror II, is suspended on a bracketttl' extending forwardly from the transverse channel .65. The third mirror, designated III is supported directly below the screen on a bracket ttiiextend ing between transverse angle ie and back angle Each of the mirrors'I, IIandHI isoi increased size in accordance with itsnearness-to the screen so that ,the lig ht pencil W111 be successively transmitted thereby toward the screen. In this manner the variance in angle of reflection of the light pencil relative to normal will be of sumcient magnitude to be easily measured on the screen. While the foregoing arrangement is best suited for the apparatus disclosed herein it will be apparent to those skilled in the art that the number of mirrors may be varied to suit the particular arran e e t of e sc a e to th wobb e plate m rr r 33t-v The. screen (ri 1) has a ce tra r ro point thereon lying in the plane B. A series of circular indicia are are concentrically arranged about the zero point and are graduated in diameter to provide a scale ca cu ated to indicate, n Oun e the amount of dynamic unbalance in a wheel being tested. The amount of dynamic unbalance is therefore measured in accordance with the distance of the spot of light from the center of the SCIQE T creen s furth r divided into quadr t by hair lines 3%] and 342 intersecting at the zero point thereof. The hair line 34! is preferably parallel to the longitudinal axis of the machine and the hair line 342 parallel to the transverse axis of the machine. These hair lines assist in locating the dynamic unbalance or the wheel.

Each mirror I, II and III (Figs. 2 to 5) is mounted in and cemented to a supporting pan 3515 having a ball 3% suitably secured to its back face 3M. The ball 34% of each pan 345- is arranged in a socket 345 in turn seciu'ed to the respect ve brackets 33,6, 33? and 33.8, heretofore referred to, so that the mirrors are fricticnally held in the desired position of adjustment within the housing.

Referring now to Figs. 2 and i, the curbings 52,9 and ital at the margins of the slot between trunnion caps T56 and H form a track on which the reciprocable hub I22 slides as the arbor 1! is swung vfrom one position to the other. The portion of eachcurbing 29 and [3B forwardly ofthe arbor is eccentric with respect totheaxis or" the trunnions T1 and it so that the distance between trunnions and curbings is greater in a horizontal direction than in a vertical direction. Consequently, the curbings I25 and E38 act as a cam to .urge the reciprocable hub I22 outwardly ion the arbor when the latter is swung into ,a horizontal position. This movement of the hub H22 introduces the ball bearing unit J25 into the counter- ;bore i138 of thegquillto prevent tilting of the spindle and to confine the latter to rotation c'o'- axially with respect to the arbor when the same ;is in horizontal position.

Referring now to Figs. 2 and v6, it will be noted .thatthe boss .Zfiii-formedas a part of the trunnion cap 16 has an upwardly extending integral arm 1359. ,A spindle centering lever 35'! is pivotally .mountedfon the arm .Siilby a stud bolt 352. .The iorward end of this lever 35:! carries aroller353 for rotation .on astud bolttdll (Figs. .1 and 2). Theroller' 353 .isadapted to engage the underside of anannular flange formed as a part of the reciprocable .hub' E22 hereinbefore mentioned .when the arbor;is held. in vertical position.

{The rearwardportion of. the lever 35! has a dependingllug 2356, see-Fig.6, into whichis threaded .a-stppbolt-tfit' carrying alock nut 35%! and is set .tozengage the arm 556 to limit upward movement .o-fsthe roller-.3515.- The rearward endor" the lever efidilisu -shapedlan'd'h'as.a pinu extending be- .twecnaitsilegs; A-rod exten ng uni-v dly boityveen-jthejlegs .0f'..the;lever i. isthreade'd into an opening-62m thepin etc (Fig, 2'). The rod-tel as seen in Fig. 4, extends down through an aperture 363 formed in an oblique end 334 of a lever 385. A compression spring 356 encompasses the lower end of the rod 3'5I to engage the lower face of the oblique end 354 of the lever 385 and is held in place by a Washer 36? and a pair of lock nuts 368.

The lever 365 is fulcrumed at its mid-section on a stud bolt 3'53 carried by a lug 3' extending upwardly from the foot It and the rearward end 312 of the lever is bent laterally as shown in Figs. 2 and 3. The end 312 of the lever 355 is engaged from below by the inner end of a foot operated lever Elia pivoted on a pin 314 supported between spaced lugs 3?.5 carried by the back angle 45 of the frame 5. The outer end of the lever 313, as seen in Figs. 2 and 3, extends through a suitable slot 376 formed in the housing [It and has a foot pedal 3i? secured thereto.

It is while the wheel is supported for rotation about a horizontal axis, as seen in Fig. 1, that the static balance is corrected by applying a compensating balance weight in a proper position on the rim of the wheel. Thereafter the wheel is swung from dotted to full line position as seen in Fig. 4 with the arbor II latched in vertical position. In this position the reciprocable hub I22 and ball bearing I24 are urged free of the quill by spring I25 and the spindle I and wheel I555 are free for universal tilting relative to the vertical axis of the arbor. The swinging bracket I80 and pole I86 thereon are swung toward the wheel to cause the drive pulley $98 to engage the tread of the tire I63 The main switch 2I4 is turned on completing the circuit to the lamp 295 and the motor switch 269 in the handle 208 is operated to complete the electric circuit to the motor to drive the pulley I98 and the wheel I65. When the wheel is rotating at the desired number of revolutions per minute the bracket I81] and pole are swung away from the wheel and the switch 289 is turned oif. Thereafter, the wheel and spindle I35 will spin under their own momentum on the self -aligning ball bearing unit I32 on the arbor H.

If the wheel is dynamically unbalanced the dynamic forces set up during the spinning of the wheel tend to tilt the same at an angle relative to its normal plane of rotation depending upon the amount and location of dynamic unbalance in the wheel. Consequently, the spindle I35 tilts on the self-aligning bearing I32, so that the wheel, spindle and wobble plate gyrate with their axis of rotation traveling in a conical orbit about the vertical axis of the arbor. When this occurs the axis of the spindle makes one circuit of the conical orbit for each revolution of the wheel.

The knob 259 is then pulled upwardly for a few moments rocking the actuating lever 24! clockwise to the dotted line position against the stop bolt 264 as seen in Figs. 2 and 3. The lever arm 245 and rocker shaft 232 are thereby rocked counter-clockwise, as seen in Figs. 4 and 6 swinging rocker arms 23 1 and 235 upwardly into a position where the ball-like surfaces of both discs 24!] engage the plate glass mirror 330 of the wobble plate. The wobble plate is thereby tilted relative to the spherical hub MI until the plate and mirror rotate in a plane parallel to the plane of travel of the center of gravity of the wheel, i. e. perpendicular to the arbor I I. The knob 269 is then released and the actuating lever and rocker arms are urged into normal position by the compression spring 265. The leaf springs I41 on the wobble plate I45 frictionally grip the spherical hub and maintain the wobble plate and mirror in adjusted position relative to the spindle I35, 1. e., at an angle relative to the spindle equal and opposite to the angular position of the spinning wheel relative to the arbor II.

The bracket I and pole I86 are again swung toward the wheel, this time without turning on the motor, so that the drive pulley I98 now en gages the tread of the tire to retard the spinning of the wheel. The handle 208 is at the same time turned (counterclockwise, Fig. 1) toward the wheel to rotate the sleeve shaft 2M and brake shoe 202 so that the linin 205 thereof frictionally engages the drive pulley to retard rotation of the latter thereby stopping the wheel. The bracket I80 and pole I86 are then swung away from the wheel which may now be rotated by hand.

The operator then steps on the foot pedal 311 to raise the inner end of the lever 373, rocking the lever 365 clockwise Figs. 3 and 4 to pull the rod 36I downwardly. The centering lever 35I is thereby rocked counterclockwise (Figs. 4 and 6) until its stop bolt 35! engages the arm 350. In this manner the roller 353 is raised into engagement with the annular flange 355 on the reciprocable hub I22 lifting the latter and ball bearing unit I24 into the counterbore I38 of the spindle quill. The spindle I 35 is thereby centered with respect to the arbor II so that the wheel and spindle will now rotate coaxially relative thereto. Therefore, when the wheel is now rotated slowly the wobble plate which is tilted on the spherical hub will simulate the wobbling action previously displayed by the wheel when it was spinning.

The lamp 295 is already illuminated and a beam of light emanating from the projector 292 is projected toward the reflector surface 293 on the wobble plate. When the wheel is positioned with the wobble plate and mirror 330 tilted up as shown in Fig. 6, the image of the light beam striking the latter will be reflected at an angle rearwardly of the normal plane of incidence N and will strike mirror I, for example, at point a. in Fig. 4.

Accordingly, the angle of reflection of the light pencil from point a on mirror I will be greater than a reflection from the centermost point of mirror I. The corresponding angle of reflection from mirrors II and III will also be greater than in the case of a dynamically balanced wheel. Consequently, the light pencil reflected from point a on mirror I and mirrors II and III will strike the lower face of the translucent panel or screen 294 to display a light spot a on the screen along hair line 34I thereof as seen in Fig. 1. The direction of the light spot from zero on the screen will indicate, by comparison with the wheel, the location of dynamic unbalance in the wheel. At the same time, the distance of the light spot from the zero point on the screen in accordance with the calibrations on the scale thereof, will indicate the amount of dynamic unbalance of the wheel.

When the wheel is positioned 90 clockwise from the position shown in Fig. 6, the axis about which the wobble plate is tilted is at right angles with respect to the plane of incidence N. The light beam reflected from the reflector surface in such case remains in the normal plane of incidence N but the angle of reflection is less than that of a balanced wheel so that the beam of light strikes mirror I at a point I) as seen in Fig. 5.

ates-est Point '5 is 96 from point d relative to the center of mirror 1 and is the same distance away from the center thereofas is point a Since point b lies in the plane of incidence N, the reflection or the light pencil therefrom is at an angle corresponding to the angle of reflectien of the light pencil in the case of a perfectly balanced wheel. However, the angle of incidence of the light 'pen oil at point I) is less than in the case of a balanced wheel. Therefore, due to the tilted position of mirrcr I, the reflection of the light pencil from point I) is reflected from mirror I in a plane diverging inwardly of the machine relative to plane R. Consequently the light pencil strikes mirrors II and III to the left of their centers as seen in Fig. 2. This causes the light spot to appeal on the transverse hair line 3 12 of th'e screen at point b thus indicating the location of 'dynainic unbalance. The radial distance of point i) from the zero point on the screen indicates the amount of dynamic unbalance according to the calibrationsbf the scale.

the wheel is turned another quarter revohitidn with the wobble plate tilted down, i. e. opposite to the position shown in Fig. 6, the image of the light beam is cast from mirror 330 forwardly of the normal plane of incidence N. Conse uently, the light team will strike mirror I in alignment with "the plane R at a point cabove the center of the mirrer as seen in 2. The light pencil reflected. from point c will strike mirrors II and HI, as well as the translucent panel or screen 294 forwardly of the centers thereof to display a light spot at c on the screen along hair line 34! as seen in Fig. 1. Point 0' is a distance from the zero point of the screen corresponding to the amount of dynamic unbalance on the calibrated scale. At the same time the location of the dynamic unbalance is indicated as being along a diametrical axis of the wheel parallel to the hair line 34[ upon which the light spot is located.

With the wheelpositioned three-quarters of a revolution from the original position referred to above, the light beam strikes the reflector surface 293 so that the image is reflected in the normal plane of incidence N at a greater angle of reflection than 'in the case of a balanced Wheel. Therefore, the light pencil will strike mirror I at point (I, which'is to the right of the-centermost point thereof as seen in Figs. Zand 5.

'Point'd is a'distan'ce from the center of -mirror Icorresponding to the distance of pointb'from the center thereof. The light pencil cast -up-- wardly from point d is in apl'ane diverging outwardly of the machine relative to the plane B (Fig. 2). Since the angle of reflection from point dig the same as in the caseof a'balanced wheel, the light pencil from point (2 will" strike mirrors Band III, aswell as the translucent panel'to the rig'htof their centers (Fig. 2). Thi 'causes the light spot to appear on the screen along transverse hair line 342 at'point'd'. The distance of point 'd from zero on the 'screen indicates'the amount ofdynamic unbalance of the wheel according to the'calibrations of the scale. Likewise the radial direction of thelight spot with respect to thezero point on'the screen indicates by comparison, the diametrical axis of 'the'wheel whereon the dynamic unbalance is located.

. From the foregoing it will'be seen that regardless "of 'the location of the dynamic unbalancein thewheel relative tothe vertical axis-of the arbor, the "light "spot "will appear on the screen are similar "anglerelativeto the zero point "thereof.

Thereiereeven though the wheel is turned about its vertical axis the location of dynamic unbalance of the wheel will be indicated correspondingly about the zero point on the screen. It is likewise apparent that irrespective of the locacation of the light spot relative to the zero point on the screen the distance of the light spot therefrom according to the calibrations of the scale will be the same in all positions of the light spot relative to the 'Zero point on the screen. In other words as the wheel is rotated the light spot will travel in a circle concentric to the zero point on the sere'en to indicate, at all times, the amount and location of dynamic unbalance in the wheel under test. The readings thus visualized on the calibrated screen are readily applied by comparison to the wheel since the latter is adiacen t to the screen.

From the foregoing comparison between the screen and wheel, correction e'f the dynamic unbalance can be made by applying the necessary balance weight to the wheel. The amount of unbalance according to the scale "on the screen is divided by two and balance weights of equal weight are selected for application to the of the wheel at opposite sides thereof. If desired the markings on the screen may be such as. to indicate one half the amount. of unbalance so that the weight. of each balance weight may be directly read off the'screen.

For the purpose of accurately determining the diametrica-l line across the wheel upon which the weights are to be applied, a pointer 400 is secured to the upper surface =I-l-l -of the housing H0 along the longitudinal axis of the machine as shown in Fig. 1. The wheel is then rotated until the lightspot appears on hair line '341 .of the screen, for instance at point a as 'hereinbefore explained. With the wheel so positioned, the dynamic unbalance of the wheel is located on a diametrical axis thereof in alignment with the pointer 40!],

When the light spot is at point a on the screen the wobble platev M5 is in the position shown in Fig. 6 in which case the wheel is out of dynamic balance along its diametricalaxisdisposed longitudinally of the machine. The wheel andwobble plate are closest to one another to the rear-of the arbor H. Thereforeone of the selected balance weights is applied to the lower or inside rim of the wheel on that side thereof corresponding to the location of the light spot c relative, to the zero .point on, the screen. The other-balance weight is applied to the upper or outside rim of the wheeland diametricallyopposite the'position of the first applied balance weight. L

Thereafter "the footpedal 311 is, released to permit spring [-25 toforcethe-reciprocable hub [22 down against the curbings l29..and'l30 on the trunnion caps -l6 and T! therebylowering ball bearing. unitv 24 out of the counterbore I38.

of the quill. The motor-isagain sWungtow-ard thefwheel'andthe drivepulley is rotated: while in engagement with the tire 'on the Wheel to spin the latter as. hereinbeforeexplained. The knob 269 is the'n'pulled up to -causethe. discs 24!] "to engage theinirror 330v on. the wobbleiplate leveling the same. tor rotation perpendicular to the vertical axis oithe arbor... Thereafter,the wheel'is stopped by applying the brake 204.4:0 the drive pulley while the latter engages the-tread of the tire I66. In the eventlthercorrectionmade as hereinbefore 'explaineid,.was successful, the quill spindl'e'i'n" this checkte'st rotates about an 15 axis coaxial with the arbor. Consequently, the wobble plate in its newly adjusted position will be parallel to the wheel and therefore, the light spot will be displayed at the zero point on the screen thus indicating that the wheel is in dynamic balance.

However, should the light spot fluctuate relative to the zero point, the location of unbalance would be indicated by the position of the light spot relative to the zero point on the screen. The weights are then shifted along the rim to overcome any deviation between the indicated location and the actual position of the weights on the wheel. If necessary a certain portion of the weight may be removed or additional amounts of weight added to the balance weights to compensate for error in the original correction.

In either event, it is apparent that the location of the dynamic unbalance is delineated on the screen after the wheel ceases spinning, and that the wheel is disposed for ready comparison with the screen so that the operator can conveniently make the necessary correction while the wheel and screen are side by side thus minimizing the possibility of error.

While the foregoing description of the mechanism and its operation refers to a specific form of construction for carrying out this invention, it is to be understood that various modifications may be made without departing from the spirit of the invention. I therefore desire to avail myself of all modifications and alternations coming within the scope of the accompanying claims.

What I claim as new and desire to protect by Letters Patent is:

1. An apparatus for checking the dynamic balance of a rotatable body comprising means for mounting said body for rotation about a reference axis and for universal tilting movement relative thereto, a reflector mounted on said body mounting means to rotate and wobble and tilt therewith and adjustable for universal tilting movement relative thereto, means for projecting a beam of light toward said reflector, means for receiving the image of said beam of light reflected from said reflector, and means for adjusting said reflector into a position normal to said reference axis while said body is rotated at a high speed and is caused to wobble about said reference axis under the influence of the dynamic unbalance of said body, whereby when said body is subsequently rotated slowly with its axis concentric to said reference axis said reflector will wobble and reflect the image of said beam of light on said image receiving means in conformity with the amount and location of dynamic unbalance of the body.

2. An apparatus for checking the dynamic balance of a rotatable body comprising means for mounting said body for rotation about a reference axis and for universal tilting movement relative thereto, a reflector adjustably mounted on said mounting means for rotation with said body and for universal tilting movement relative thereto, means for spinning said body to cause it to Wobble under the influence of the dynamic unbalance thereof, means for adjusting said reflector with respect to said mounting means for rotation in a plane normal to said reference axis while said body is spinning, means for subsequently righting said mounting means for supporting said body for rotation about said reference axis without disturbing the adjusted position of said reflector, means for projecting a beam of light from a fixed source toward said reflector, and means for receiving the image of said beam of light reflected from said reflector to visibly indicate the amount and location of dynamic unbalance of the body.

3. An apparatus for checking the dynamic unbalance of a rotatable body comprising means for mounting said body for rotation about a reference axis and for universal tilting relative thereto, a reflector carried by said mounting means for rotation therewith and for universal tilting movement relative thereto, means for projecting a beam of light from a fixed source toward said reflector, means disposed in fixed relation relative to said reference axis for receiving the image of said beam of light reflected from said reflector, means for tilting said reflector relative to said mounting means into a position normal to said reference axis while said body is rotated at a high speed and is caused to wobble about said reference axis under the influence of the dynamic unbalance of the body, and means for subsequently holding said mounting means and body for rotation concentric to said reference axis without disturbing the tilted position of said reflecto relative to said mounting means and body whereby the image of said beam of light is reflected upon said image receiving means in conformity with the amount and location of the dynamic unbalance of the body.

4. An apparatus for testing the dynamic balance of a rotatable body including an arbor, means for supporting said body on said arbor for free rotation and universal tlting relative thereto, means for rotating said body and supporting means whereby dynamic unbalance of the body will cause a wobbling action of the body and supporting means relative to the axis of said arbor, and an optical indicator comprising means for projecting a beam of light toward said body, a reflector connected to said body supporting means to rotate and wobble and tilt therewith, said reflector being adjustable for universal tilting movement relative to said body supporting means and adapted to intercept said light beam, means for tiltably adjusting said reflector to a position normal to said arbor during high speed rotation and wobble movement of said body, and a screen arranged to receive an image of the reflected light beam for visually indicating the amount and location of dynamic unbalance of said body upon slowly rotating said body and the thus tiltably adjusted reflector.

5. An optical indicator for balance testing apparatus comprising means for supporting a body for free rotation and universal tilting movement relative to a predetermined axis, means for spinning said body whereby dynamic unbalance thereof causes the body to wobble relative to said predetermined axis, a reflector carried by said body supporting means for rotation and wobble movement with said body and tiltably adjustable relative thereto, means for tiltably adjusting said reflector for rotation in a plane normal to said predetermined axis while said body is Wobbling relative thereto, means for projecting a beam of light toward said reflector, and a screen arranged to receive an image of said beam of light from said reflector whereby when said body ceases rotating and is disposed normal to said predetermined axis, the amount and location of dynamic unbalance of said body is visually portrayed on the screen in accordance with 17 the adjusted angle of tilt of the reflector relative tosaid predetermined axis.

6. A wheel balancer comprisin means adapted to have a wheel mounted thereon for testing, means for supporting said mountin means with its axis normally in an upright position and permitting the wheel thereon to wobble when it has been set spinning, a reflector carried by said mounting means to rotate in unison with the wheel and adapted to be tilted with respect to said mounting means, means for engaging said reflector while the wheel is spinning and wobbling to tilt the reflector into a plane perpendieular to the normal upright position of said mounting means, said supporting means including an auxiliary means for engaging said mountin: means to sup-port the wheel for rotation about apredet'ermined axis, means for projecting' -a beam of light toward said reflector, and means for receiving the reflected image of said light beam whereby'to indicate the amount and location of dynamic balance of said Wheel.

7. An apparatus for checking the dynamic balance of a rotatable body comprising an arbor, a quill mounted for rotation and universal tilting movement on said arbor, said quill being adapted to have the body to be checked mounted thereon for rotation and tilting movement therewith, means for rotating said body and quill whereby unbalance of the body will cause a wobble action of the body and quill about the axis of said arbor, a-reflector plate carried by said quill for rotation and wobble movement therewith and tiltable relatively thereto, means for projecting a beam of lightltoward said reflector plate, a screen arranged to receive the reflected image of said beam of light from said reflector plate, and means for tiltably adjusting said reflector plate for rotation in a plane perpendicular to the axis of said arbor while said body and quill are rotated, whereby when the body and quill are subsequently rotated slowly concentric to said arbor axis any adjusted tilt of said reflector plate will simulate the wobbling action of said body and quill and will reflect said beam of light on said screen to delineate thereon the amount and location of any dynamic unbalance of the body.

'8. An apparatus for checking the dynamic balance of a rotatable body comprising a vertical arbor, a spindle for supportin said body on said arbor for free rotation and universal tilting relative thereto, means for rotating said body and spindle whereby the dynamic unbalance of the body will cause a wobbling action of the body and spindle relative to the vertical axis of said arbor, a reflector carried by said spindle and tiltable relative thereto, means for projecting a beam of light toward said reflector, a charted screen arranged to receive an image of said beam of light from said reflector, means for adjusting said reflector for rotation in a plane perpendicular to the vertical axis of said arbor while the axis of said spindle is inclined relative to the arbor due to wobbling of the body, and means for engaging said spindle for causing the same and said body to rotate coaxially with respect to said arbor whereby said reflector will simulate said wobbling action of the body and reflect the image of said light beam on to said charted screen to delineate thereon the amount and location of dynamic unbalance in the body.

9. An apparatus for checking the dynamic balance of a rotatable body comprising a spindle for supportin said body for free rotation about a vertical axis and for universal tiltin movement relative thereto, reflector means carried by and surrounding said spindle for rotation co'axially therewith and tiltable relative thereto, means for projecting a beam of light toward said reflector, a screen arranged to normally receive at a zero point thereon an imageoi said beam of light from said reflector, means for rotating said body and spindle whereby dynamic unbalance of said body will cause precession orthe axis of rotation of the body and spindle relative to said verticalaxis, and means for tilting said reflector to dispose its axis ve'rtical during precession of the axis of rotation oi the body and spindle whereby when said body andspindle are subsequently rotated slowly about said vertical axis said reflector will cast the image said beam of light upon said screen in a radial direction relative to said zero point corresponding to the location of the dynamic unbalance in the body.

10. An apparatus for checking the dynamic balance of a rotatable body comprising a spindle for supporting said body for free rotation and universal tilting movement relative to the normal axis of rotation thereof, reflector means carried by-and surrounding said spindle for rotation coaxially there""ith and tiltable relative thereto, means for projecting a'beam or lighttoward said reflector, a screen arranged to receive at a zero poih't'thereo'n an image oi-said beam-or light from said refieet means for rotating said body and spindle whereby dynamic unbalance of said body will cause precession of the axis of rotation of the body and spindle relative to the normal-axis of rotation thereof, means for tilting said reflector to dispose its axis of rotation parallel to the-normal axis or rotation of said spindle during recession of the axis of rotation of the body and spindle, and meansforengaging said spindle for aligning the same with the normal axis of rotation thereof whereby said reflector will castthe image of said beam of light upon said screen in a radial direction relative to said zero point corresponding to the location or the dynamic unbalance in the body.

11-. An apparatus :for checking the dynamic balance or a'rot'atable body comprisin an arbor,

means for mounting said body on said arbor for universal tilting movement, detector means carr'iedbys'aid mounting means and having a light reflecting surface surrounding the same for rotation coaxially therewith and for adjustment relative thereto, means for projecting a light beam in a predetermined plane of incidence to- Ward said light reflecting surface and at a predetermined angle with respect to said surface whereby an image of the light beam is reflected therefrom in a plane congruent to the plane of incidence, means for rotating said body and mounting means therefor whereby dynamic unbalance of the body will cause wobbling of the body and mounting means about the vertical axis of said arbor, means for adjusting said detector means into a position with its axis parallel to the axis of said arbor while said body and mounting means therefor are wobbling, means for subsequently aligning the axis of said mounting means with the axis of said arbor whereby said detector means will simulate the wobbling of said body to cause the image of said light beam reflected by the light reflecting surface thereof to deviate from said predetermined angle and plane of incidence in accordance with the amount and location of dynamic unbalance in the body, and a light receiving surface arranged to intercept the image of said light beam reflected from said lightreflecting surface to thereby register the amount and location of dynamic unbalance of said body.

12. An apparatus for checking the dynamic balance of a rotatable body comprising a vertical arbor, a spindle for supporting said body on said arbor for free rotation and universal tilting relative thereto, reflector means carried by and surrounding said spindle for tiltin movement relative thereto and for rotation coaxially therewith, means for projecting a beam of light toward said reflector, a screen arranged to receive at a zero point thereon an image of said light beam from said reflector, means for rotating said body and spindle whereby dynamic unbalance of said body will cause a wobbling action of the body and spindle about the axis of said arbor, means for engaging said reflector for tilting the same relative to said spindle for rotation in a horizontal plane while said body is wobbling whereby when said body is subsequently rotated with its axis concentric with the axis of said arbor the reflector will simulate th wobbling action of the body, and means for stopping the rotation of said body and reflector so that the latter reflects the image of said light beam in a direction radially relative to said zero point and at a distance therefrom to indicate the amount and location or dynamic unbalance of the body.

13. In an apparatus for checking the dynamic unbalance of a rotatable body including means for supporting a wheel for free rotation about a predetermined axis and universal tilting movement relative thereto and means for rotating said wheel at a high speed to cause a dynamically unbalanced wheel to wobble relative to said predetermined axis in accordance with the amount and location of dynamic unbalance in such wheel, the combination therewith of an optical indicator comprising a wobble plate operatively connected with said wheel supporting means for rotation coaxially with said Wheel and for tilted adjustment relative thereto, means for adjusting said wobble plate for rotation in a plane normal to said predetermined axis as said wheel is wobbling relative thereto, means for projectin a beam of light toward said wobble plate, a screen having calibrations thereon, said wobble plate having a light reflecting surface for intercepting said beam of light and for reflecting the same toward said supporting means.

14. In a balance tester for a rotatable body including means for supporting said body for rotation about a reference axis and for tilting action with respect thereto during spinning of the body so that dynamic unbalance thereof causes the body and supporting means to wobble relative to the reference axis, the combination therewith of an optical indicator comprising a reflector carried by said supporting means for rotation therewith and adapted to be tiltably adjusted relative thereto, means for adjusting said reflector for rotation perpendicular to said reference axis during spinning and wobbling of said body and supporting means whereby said reflector assumes a tilted position relative to the body, means for holding said supporting means coaxially with said reference axis, means for projecting a light beam from a fixed source toward said reflector whereby an image of said beam is reflected therefrom in ac: cordance with the position of adjustment thereof, and means disposed in fixed relation relative to said body when it is held by said holding means for receiving an image of said light beam at a predetermined point thereon when said reflector is parallel to said body whereby when said reflector is in tilted position with respect thereto said image is reflected toward said image receiving means in a direction radially relative to said predetermined point and at a distance therefrom corresponding to the location and amount of dynamic unbalance of said wheel.

TRACY CARRIGAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Holmes May 23, 1944 

